Air filter



w 15528 397 May 1 r F. K. EWING ET AL AIR- FILTER Filed Oct 12, 1925 Patented May 10, 1927.

UNITEDSTATES PATENT OFFICE.

FRANK K. EWING, OF WORCESTER, MASSACHUSETTS,'.AND STANLEY R. CUMMINGS, OF CANTON, OHIO, ASSIGNORS TO THE ,HOOVER COMPANY, CORPORATION OF OHIO.

AIR rim'na.

Application filed October 1 This invention relates in general to improvements in air filters, and in particular to the production of an efiicient and reliable means for separating dust from air by means of a fabric that can be easily mnufactured,

and which lends itself readily to the operations necessary to form it into bags such as are in common use on domestic vacuum cleaners. I

investigation hasshown that a mass of loose and slightly twisted textile fibres, such as cottombatting, forms a very effective means for the separation of dust from air. Cotton-batting, however, is quite unwieldy, l5 and due to its lack of tensile strength is not afit material from which to form bags which must retain and hold the dirt collected un-, til it can be convenientlyi-emmed.

An object of this invention is to produce a fabric which will approximate the airfilteringcharacteristics of cotton-batting, and at the same time possess suificient strength in-' all directions to render it suitable for dust bags. Another object is the production of a fabric of reasonable thickness and weight which will possess desirable air filtering characteristics.

Another object is the production of a multi-ply interwoven fabric in which the filling 0 yarns are very loosely twisted and held to? gether by means of warp yarns which give the fabric the necessary tensile strength and finish. I

With the foregoing and relatedobjects in view the invention consists in the novel combination and arrangementof the parts of the fabric, and in the novel character of the constituent parts thereof.

. In the accompanying drawings illustrating the invention:

Figure 1 illustrates the air filter shown in use with the common domestic type of vacuum cleaners;

Fig. 2 is a transverse section 4 fabric forming the filter;

Fig. 3is a face view of the finished fabric.

Referring to the drawings, the air filter consists of the fabric which for use with the ordinary type of suction cleaner is formed in the she. e of a bag 10 which can be readily attache or detached from the suction cleaner 11. i

The cloth from which the dust bag is made, is referred to as a .m-ulti-ply interwoven fabric, inasmuch as it consists of a plurality of distinctdayers' of filling yarn through the 2, 1925. Serial No. 61,960

which are held together by means of warp yarns the character of which will be described later in detail.

In the air filter shown in thedrawings the fabric is composed: of two layers A and B, which form the face and back of the fabric, respectively. It is to be understood, however that two layers are shown for the purpose of illustration only and that our invention is not limited to anyparticular number. of layers. I

The layer A is made up of filling stutter yarns 12 and face filling yarns 13 arranged alternately and secured together by the warp face yarns 14 which pass over two stuffers 12 and one filling 13 and then under one filling. The layer B is made up in the same manner and secured'together by r the warp back yarns 15. The two layers are then firmlybound together by the warp binders 16 which passover the face filling yarns 13 in one layer and then over the filling yarns 13 in the other layer. 7

The unique and-novel filtering properties of the fabric are due primarily to the char acteristics ofthe filling yarns. In order to approximate as closely as possible in a woven fabric the structure of cotton-batting, these yarns are very loosely'twisted; for example, not more than 20 turns per inch and preferably between i and 16, merely suflicient to give themthe necessary strength to stand up under the weaving process.

The functions of the warp threads which are all hard twisted are to hold the loosely twisted filling yarns in. place and to give the resulting fabric suificient strength to withstand the strains to which it is'naturally subjected in use.

We claim A multiple ply fabric for filters comprising loosely twisted yarns, each ply comprising alternately arranged relatively large and smallloosely twisted yarns, each ply ofi'setto place a large yarn of one ply under a small yarn of an adjacent ply, and warp yarns securing the loosely twisted yarns in place.

Signedat Worcester, in the county of Worcester, and State of Massachusetts, this 2ndday of October A. D., 1925.

FRANK K. EWING.

Signed at North Canton, in the county of Stark, and State of Ohio, this 5 day of Oct.- A. D, 1925. 

